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H2O2-producing commensal streptococci disrupt Streptococcus mutans-Candida albicans synergism

2026-05-01T00:00:00Z

Title: H2O2-producing commensal streptococci disrupt Streptococcus mutans-Candida albicans synergism Authors: Shao, Hongfei; Yoo, Hanyeol; Cai, Jian-Na; Jung, Hee-Young; Kang, Chung-Min; Jeon, Jae-Gyu; Kim, Dongyeop Abstract: Microbial homeostasis is maintained by the antagonistic capacity of commensal bacteria against cariogenic pathogens. In the oral cavity, commensal Streptococcus, dominant colonizers of the tooth surface, can produce hydrogen peroxide (H2O2), modulating virulent cross-kingdom biofilm formation. To investigate their ecological role, clinical isolates from dental plaque were compared with reference strains, including Streptococcus oralis ATCC 35037 and S. oralis subsp. tigurinus J22 to determine their H2O2-producing capabilities. The antagonistic potential of S. oralis against Streptococcus mutans and Candida albicans was evaluated using microbial and biochemical assessments. In a saliva-coated hydroxyapatite disc model, S. oralis strains were co-cultured with S. mutans and C. albicans. A high H2O2-producing S. oralis J22 inhibited EPS formation in S. mutans and yeast-to-hypha transition in C. albicans, thereby reducing EPS-mediated bacterial-fungal cell colocalization. Time-lapse confocal imaging revealed that S. oralis J22 dominated the biofilm through H2O2-mediated antagonistic interactions. In contrast, the inhibitory effect of S. oralis strains lacking the spxB gene on cross-kingdom biofilms was significantly reduced. These data provide ecological insights into how physicochemical properties of early colonizing commensals shape the structure and virulence of cross-kingdom oral biofilm through antimicrobial-mediated antagonistic activity.IMPORTANCEThe co-existence of S. mutans and C. albicans accelerates the development of severe early childhood caries, particularly under frequent sucrose exposure. This study demonstrates that early colonizing and antimicrobial-producing oral commensal bacteria can disrupt these pathogenic interactions by modulating their physicochemical associations. These findings highlight the potential of enhancing commensal bacteria as part of novel caries prevention strategies. Further characterization of the functional oral microbiota, especially clinically relevant oral commensals, could advance the development of diagnostic biomarkers and microbiome-targeted therapeutics to prevent painful and costly oral diseases. The co-existence of S. mutans and C. albicans accelerates the development of severe early childhood caries, particularly under frequent sucrose exposure. This study demonstrates that early colonizing and antimicrobial-producing oral commensal bacteria can disrupt these pathogenic interactions by modulating their physicochemical associations. These findings highlight the potential of enhancing commensal bacteria as part of novel caries prevention strategies. Further characterization of the functional oral microbiota, especially clinically relevant oral commensals, could advance the development of diagnostic biomarkers and microbiome-targeted therapeutics to prevent painful and costly oral diseases.

Evaluation of developmental defects of enamel and differential diagnosis from dental caries using quantitative light-induced fluorescence technology: A cross-sectional investigation

2026-04-01T00:00:00Z

Title: Evaluation of developmental defects of enamel and differential diagnosis from dental caries using quantitative light-induced fluorescence technology: A cross-sectional investigation Authors: Lee, Seong Joon; Choi, Hyung-Jun; Lee, Jaeho; Song, Je Seon; Lee, Ko Eun; Kang, Chung-Min; 이승준 Abstract: Objectives: Dental caries and developmental defects of enamel (DDE) are common conditions that impact oral health. Quantitative light-induced fluorescence (QLF) is widely used for detecting dental caries, but its ability to identify DDE remains unclear. This study aimed to investigate fluorescence differences among sound, carious, and DDE-affected teeth using QLF, and to differentiate white hypomineralization from incipient caries. Methods: Data from 704 teeth in 137 patients under 20 years old were analyzed. QLF images were acquired, and fluorescence parameters were measured. Statistical tests included Chi-square, Fisher's exact, Mann-Whitney, Kruskal-Wallis, Linear mixed-effects models, and receiver operating characteristic (ROC) analyses. Results: Delta F values progressively decreased and Delta R values increased from sound to DDE-affected to carious teeth (p < 0.001). Within DDE, fluorescence changes differed significantly according to defect subtype, with combined defects showing the greatest mineral loss and bacterial activity (p < 0.001 for Delta F, p = 0.008 for Delta R). White hypomineralization showed higher Delta F values and lower Delta R values than yellow/brown hypomineralization (p < 0.001). Significant fluorescence differences were observed between white hypomineralization and International Caries Detection and Assessment System scores 1 and 2 lesions (p < 0.001). ROC analysis revealed excellent accuracy for distinguishing white hypomineralization from incipient caries, with areas under the curve of 0.970 for Delta F mean and 0.979 for Delta R mean. The optimal cutoff values were -7.65 for Delta F mean and 23.50 for Delta R mean, respectively. Conclusions: QLF provides effective quantitative support for differentiating DDE from incipient caries. Clinical Significance: Quantitative light-induced fluorescence provides objective parameters for differentiating developmental defects of enamel from incipient dental caries. By offering quantitative cutoff values, this approach supports more accurate diagnosis of clinically ambiguous white spot lesions, reduces the risk of overtreatment, and facilitates prevention-oriented and minimally invasive treatment planning in routine dental practice.

Impact of Reimbursement Expansion on Clinical Environment and Caregiver Satisfaction in Dental Care for Pediatric and Adolescent Patients with Disabilities: A Pilot Study at Yonsei University Dental Hospital

2026-02-01T00:00:00Z

Title: Impact of Reimbursement Expansion on Clinical Environment and Caregiver Satisfaction in Dental Care for Pediatric and Adolescent Patients with Disabilities: A Pilot Study at Yonsei University Dental Hospital Authors: 이소담; 이고은; 정지은; 이승준; 강정민; 송제선; 최형준; 이재호 Abstract: This study aimed to investigate caregivers’ treatment satisfaction and clinical changes after the expansion of the additional reimbursement system for dental treatment for children with disabilities. A cross-sectional survey was conducted from April to May 2025 among 106 caregivers of pediatric patients with registered disabilities, including intellectual disability, brain lesion-related disabilities, and autism spectrum disorder. The 30-item questionnaire covered demographics, dental history, system awareness, clinical changes, and satisfaction. Statistical analyses included the Wilcoxon signedrank test, Fisher-Freeman-Halton exact test with Monte Carlo estimation, the binomial test, and the Poisson rate test, with the significance level set at α = 0.05. After expansion, the most common dental visit interval shifted from every 6 months to every 3 – 4 months (p < 0.0001). Caregivers reported improvements in treatment proactivity (p = 0.002) and treatment diversity (p < 0.0001), as well as overall satisfaction with dental care (p < 0.0001). This study suggests improvements in the clinical environment and satisfaction following the policy expansion. In the future, large-scale and longterm studies may help enhance the reliability of the findings and clarify their broader clinical implications.

Longitudinal analysis of oral microbiome changes during the neonatal period in full-term and preterm newborns

2025-12-01T00:00:00Z

Title: Longitudinal analysis of oral microbiome changes during the neonatal period in full-term and preterm newborns Authors: Lee, Taeyang; Kim, Hyun-Yi; Han, Jung Ho; Shin, Jeong Eun; Song, Na-Young; Chung, Won-Yoon; Kang, Chung-Min Abstract: BackgroundThe neonatal period is critical for oral microbiome establishment, but temporal patterns in preterm newborns remain unclear. This study examined longitudinal microbiome changes in full-term and preterm newborns and assessed perinatal and clinical influences.MethodsOral swabs were collected from 98 newborns (23 full-term, 75 preterm). Samples were obtained at birth and Day 2 for full-term, and at birth, Day 7, and Day 28 for preterm newborns. 16S rRNA gene sequencing was used to analyze microbial diversity, taxonomic shifts, and virulence-related genes.ResultsPreterm newborns showed persistently lower alpha-diversity and delayed succession compared with full-term newborns. Full-term infants transitioned rapidly from Proteobacteria-dominant to Firmicutes- and Actinobacteria-rich communities, while preterm infants maintained Proteobacteria longer. Diversity in preterm newborns was significantly affected by gestational age, birthweight, delivery mode, feeding type, and beta-lactam exposure. Breastfeeding supported more stable diversity, whereas cesarean delivery and formula feeding reduced diversity. Functional profiling revealed greater abundance of virulence-associated genes in preterm newborns, suggesting differences in early host-microbe interactions. ConclusionsPreterm newborns exhibit delayed oral microbiome development, influenced by multiple modifiable factors. Supportive strategies, such as breastfeeding and prudent antibiotic use, may help foster microbial stability and potentially reduce infection risk in this vulnerable population.